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Biomechanical efficiency is impaired in patients with chronic heart failure
Author(s) -
Witte Klaus K.,
Levy Wayne C.,
Lindsay Kenneth A.,
Clark Andrew L.
Publication year - 2007
Publication title -
european journal of heart failure
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.149
H-Index - 133
eISSN - 1879-0844
pISSN - 1388-9842
DOI - 10.1016/j.ejheart.2007.05.004
Subject(s) - anaerobic exercise , medicine , heart failure , oxygen , steady state (chemistry) , cardiology , vo2 max , workload , heart rate , physical therapy , chemistry , blood pressure , organic chemistry , computer science , operating system
Patients with chronic heart failure (CHF) have a lower peak oxygen consumption (p V O2 ) than normal subjects, and for a given quantity of work, have a lower total oxygen consumption ( V O2 ) than controls. This apparent increase in biomechanical efficiency (BE) might be due to a higher proportion of anaerobic metabolism which, although leading to lower V O2 during steady state exercise, must be compensated for during recovery. Methods 13 patients with stable CHF and 12 controls underwent peak cycle exercise testing followed by three separate steady state exercise tests at 15%, 25% and 50% of the peak workload in random order. Oxygen consumption at steady state, deficit (during onset) and debt (during recovery) were calculated. BE was estimated as the total oxygen required to perform a given quantity of work. Results Patients had lower p V O2 and peak workload than control subjects. Absolute oxygen deficit and debt as a percentage of total oxygen consumed during the steady state tests was the same in both groups. However, once controlled for workload, V O2 deficit, debt and uptake at steady state were greater in patients than controls for the tests at 15% and 25% of peak. BE was inversely related to peak oxygen consumption in controls and patients. Conclusions Patients with CHF have impaired BE at low work loads when compared with normal subjects.